After per-port vlan stats, vlan stats should be released
when fail to add vlan

Fixes: 9163a0fc ("net: bridge: add support for per-port vlan stats")
CC: bridge@lists.linux-foundation.org
cc: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
CC: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: NZhang Yu <zhangyu31@baidu.com>
Signed-off-by: NLi RongQing <lirongqing@baidu.com>
Signed-off-by: NNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>